Ohio - Criteria: C (architecture/engineering)
| Abbott-Page House |
| Acton House |
| Adams Covered Bridge |
| Adams, Demas, House |
| Adams, George W., House |
| Adams, G., House |
| Adams-Gray House |
| Adams, John And Maria, House |
| Adams School |
| Adams Street Double House |
| Ada Pennsylvania Station and Railroad Park |
| Adelbert Hall, Case Western Reserve University |
| Adena Court Apartments |
| Adena (Thomas Worthington House) |
| Adgate Block |
| Administration Building, Lake Erie College |
| Agler-La Follette House |
| Aigler Alumni Building |
| Akey, James, Farm |
| Akron-Fulton International Airport Administration Building |
| Akron Jewish Center |
| Akron Post Office and Federal Building |
| Akron Public Library |
| Akron Rural Cemetery Buildings |
| Akron Y.M.C.A. Building |
| Alameda Apartments |
| Alcazar Hotel |
| Aldrich, Aaron, House |
| Alexander, Dr. William S., House |
| Alexandra, The |
| Alkemeyer Commercial Buildings |
| Alkire House |
| Allen County Courthouse |
| Allen, Darlon, House |
| Allen, Dr. Peter, House |
| Allen, Lyman, House And Barn |
| Allen Memorial Medical Library |
| Alliance Bank Building |
| Alling, Francis D., House |
| All Saints Episcopal Church |
| All Souls Unitarian-Universalist Church |
| Alms and Doepke Dry Goods Company |
| Ambler Heights Historic District |
| American Can Company Building |
| American Insurance Union Citadel (Palace Theatre Amendment) |
| Ames, Charles Rice, House |
| Amherst Town Hall |
| Anderson Brothers Department Store |
| Anderson, Judge William Shaw, House |
| Anderson, Levi, House |
| Anderson Schoolhouse |
| Anderson-Shaffer House |
| Anderson, William Marshall, House |
| Andres, Charles, House |
| Andrews, Ebenezer, House |
| Anna-Dean Farm |
| Anna Town Hall |
| Annis, John M., House |
| Ansel Road Apartment Buildings Historic District |
| Antioch Hall, North And South Halls |
| Antioch Temple |
| Antlers Hotel |
| Antwerp Norfolk and Western Depot |
| Apostolic Bethlehem Temple Church |
| Arcade Hotel |
| Archwood Avenue Historic District |
| Archwood Congregational Church |
| Arendt-Seymour House |
| Arlington Avenue District |
| Arlington Hotel |
| Armory-Latisona Building |
| Armstrong Farm |
| Armstrong, Joseph, Farm |
| Arrowston |
| Artz House |
| Artz, John, Farmhouse |
| Ashland Avenue Baptist Church |
| Ashland County Courthouse |
| Ashtabula County Courthouse Group |
| Ashtabula Harbor Light |
| Ashtabula Harbour Commercial District |
| Ashville Depot |
| ASM Headquarters and Geodesic Dome |
| Athens County Infirmary |
| Athens Downtown Historic District |
| Athens Governmental Buildings |
| Athens State Hospital |
| Athens State Hospital Cow Barn |
| Atwater Congregational Church |
| Auglaize County Courthouse |
| Augspurger, Frederick, Farm |
| Augspurger, John, Farm No. 1 |
| Augspurger, John, Farm No. 2 |
| Augspurger, Samuel, Farm |
| Aullwood House and Garden |
| Ault-Weygandt Farm |
| Aurora Center Historic District |
| Aurora Train Station |
| Ausenbaugh-McElhenny House |
| Austin, Eliphalet, House |
Data from United States Park Service and Wikidata
